Figure 3.

Bicuculline significantly affects pheromone-mediated navigation behavior. (a-c) Behavioral measurements on unoperated (gold), saline-injected (cyan) and bicuculline-injected
(red) moths in a wind tunnel supplied with (a) pheromone or (b) solvent control (cyclohexane).
Neither bicuculline nor saline injection affected a moth's ability to be motivated
to fly (wing-fanning) or make upwind progress. A significantly lower percentage of
bicuculline-injected moths (n = 12) displayed close hover, source contact and abdomen curl, compared with the unoperated
(n = 10) and saline-injected (n = 15) groups (G test: p < 0.05). Under cyclohexane, all moths showed wing-fanning behavior, but only 30–50%
of moths in each group (n = 10, 6, 9 for unoperated, saline-injected and bicuculline-injected, respectively)
progressed upwind and an even lower percentage displayed close hover and source contact.
None of the animals that came close to the source displayed abdomen curl. (c) The
effects of bicuculline on close hover, source contact and abdomen curl shown in (a)
were reversed after recovery for at least 2 h in a dark environmental chamber (n = 8, 7, 9 for unoperated, saline-injected and bicuculline-injected, respectively).
Different letters within a behavioral category denote statistical significance (G test:
p <0.05). (d-i) Flight-track analysis on unoperated (d, g), saline-injected (e, h) and bicuculline-injected
(f, i) moths with pheromone or solvent control in the wind tunnel. (d, e) Using pheromone
as the odor source, the unoperated and saline-injected moths flew directly toward
the odor source, thus resulting in approximately straight flight tracks (top), centrally
distributed transit probability (middle panels) and track-angle distribution histograms
(bottom panels) with a prominent peak at zero degrees (mean ± SEM). The central distribution
of transit probability is further demonstrated with a summed bar graph (along the
wind direction) located to the right of the pseudocolor plots, showing a single peak
at the center. (f) Bicuculline-injected moths, on the other hand, markedly diminished
the central peak as well as the tracking frequency peak at zero degree track angle.
(g-i) Replacing the pheromone with solvent control (cyclohexane) in the wind tunnel
resulted in unanimous 'looping' flight tracks in all three treatment groups, reflecting
an engagement of cross-wind casting in these moths, which is also shown in the randomly
distributed transit probability of occupancy as well as in the bimodal distribution
of track angle histograms.